I agree with the direction of putting QOS on the egress side but
rather than do fair-queue (if that's what you meant) please
use a MQC service-policy like this:
policy-map queueing
class calss-default
fair-queue
int multilink X
service-policy out queueing
Then you can do show policy map interface Multilink X and see it.
There have been bugs before with how Cisco does a virtual tx ring
to make sure all proper queuing is done at the bundle level before
assigning the sequence number to the frame to reduce reorders downstream.
Other than that the most common problem we see if people feel a FE or
GE to a nxT1 bundle and the microburst cause the drops.
You can try tweaking the queue-limit in the default class to see if it
can help absorb those microburst.
To prove it's microburst in that default class put a policer at a rate
close to the nxT1 bundle speed and set transmit for conform,exceed,viloate.
Then watch the policy for exceed/violate. If you see them you know you
are microbursting coming off the LAN.
Rodney
On Mon, Sep 29, 2008 at 11:37:12AM +0930, Ben Steele wrote:
As a test try putting some fair-queuing on your multilink interface and see
if the problem lessens/goes away, play with the values until you find your
sweet spot.
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Church, Charles
Sent: Monday, 29 September 2008 11:02 AM
To: cisco-nsp@puck.nether.net
Subject: [c-nsp] Output drops on PPP multilink int
Anyone,
Seeing lots of output drops on ppp multilink interfaces across our
network, all multiple T1s, on 2600s through 3800 routers. The
underlying T1 serial ints don't have many drops (maybe 0.1% of those
found on the multilink int worst case). Any idea what would cause drops
on the interface? There is no QOS or anything like that on the mu2 int,
just an inbound ACL. Google search didn't really turn up anything too
useful. CPU and memory on the routers look pretty good. T1s seem
pretty clean, the couple routers I watched closely didn't have any T1
errors during the time frames when drops where occuring. All are
running recent 12.3 or 12.4 mainline releases. Utilization on the
multilink interface was low (under 25%), at least according to the 30
second load interval.
Thanks,
Chuck
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